CVE-2008-2371 in pcre
Summary
by MITRE
Heap-based buffer overflow in pcre_compile.c in the Perl-Compatible Regular Expression (PCRE) library 7.7 allows context-dependent attackers to cause a denial of service (crash) or possibly execute arbitrary code via a regular expression that begins with an option and contains multiple branches.
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Analysis
by VulDB Data Team • 08/14/2019
The vulnerability identified as CVE-2008-2371 represents a critical heap-based buffer overflow within the Perl-Compatible Regular Expression library version 7.7. This flaw exists in the pcre_compile.c source file and demonstrates a fundamental weakness in how the library processes regular expressions containing specific structural patterns. The vulnerability manifests when a regular expression begins with an option specifier and contains multiple branching constructs, creating a condition where memory allocation calculations become corrupted. The underlying technical flaw stems from inadequate bounds checking during the compilation phase of regular expressions, where the library fails to properly validate the memory requirements for complex expression structures. This particular implementation issue allows attackers to manipulate the heap memory layout through carefully crafted regular expressions that exploit the library's internal memory management routines.
The operational impact of this vulnerability extends beyond simple denial of service to potentially enable arbitrary code execution in vulnerable environments. When exploited, the buffer overflow can cause the application using PCRE to crash or terminate unexpectedly, leading to service disruption and denial of service conditions. However, the more severe implications arise from the potential for remote code execution, where attackers could leverage this vulnerability to inject and execute malicious code within the application context. The context-dependent nature of this vulnerability means that exploitation requires specific conditions to be met, including the use of particular regular expression patterns that trigger the memory corruption. This characteristic makes the vulnerability particularly dangerous because it can be triggered through user-supplied input that gets processed through the PCRE library, such as web form submissions, log file parsing, or any application that accepts regular expressions as input.
Security professionals should recognize this vulnerability as a classic example of CWE-121, which describes heap-based buffer overflow conditions, and it aligns with ATT&CK technique T1059.007 for input validation bypass through regular expression manipulation. The vulnerability's exploitation pathway demonstrates how seemingly benign input processing can become a vector for serious security compromise. Organizations using PCRE library versions 7.7 or earlier should prioritize immediate remediation through library updates, as the vulnerability affects numerous applications and systems that depend on regular expression processing. Mitigation strategies include implementing proper input validation and sanitization at application boundaries, using updated versions of the PCRE library that contain patched memory handling routines, and deploying intrusion detection systems that can identify suspicious regular expression patterns. Additionally, application developers should consider implementing sandboxing mechanisms for regular expression processing and establishing robust error handling to prevent exploitation attempts from causing system-wide failures. The vulnerability highlights the importance of thorough security testing for mathematical and parsing libraries that handle user input, as these components often become targets for sophisticated exploitation techniques due to their critical role in system operations.